Photographic emulsions sensitized with sulfonium salts and alkylene oxide polymers



United States Patent PHOTOGRAPHIC EMULSIONS SENSITIZED WITH SULFONIUMSALTS AND ALKYLENE OXIDE POLYNIERS Jonas John Chechak, John Saga], Jr.,and Albert C. Smith, Jr., Rochester, N. Y., assignors to Eastman KodakCompany, Rochester, N. Y., a corporation of New Jersey No Drawing.Application December 1, 1955 Serial No. 550,496

14 Claims. (Cl. 96107) This application relates to photography andparticular- 1y to sensitizing photographic emulsions.

It is well known that silver halide emulsions may be chemicallysensitized with a variety of materials in order to increase the speedand generally the gamma of the emulsion, as opposed to opticalsensitization in which the optical range of sensitivity is increased.Chemical sensitization usually results either from the formation ofsilver sulfide on the surface of the silver halide crystal, thusincreasing sensitivity, or from the formation of small amounts of silverfrom the reduction of silver halide. Other classes of compounds, such ascertain ethylene oxide condensation products and certain cationicsurfaceactive salts increase sensitivity of silver halides withoutapparently entering into chemical combination with the silver halide.

Carroll and Allen U. S. Patent 2,275,727 describes the chemicalsensitizing of silver halide emulsions containing sensitizing dyes,using cationic surface-active sulfonium salts. These sulfonium salts areincorporated in the emulsion before, simultaneously with, or after theoptical sensitizing dye and increase the speed of the emulsion sosensitized.

We have now found that the sensitivity of silver halide emulsions whichhave been sensitized with alkylene oxide polymers, with or withoutoptical sensitizing dyes, may be further increased by the use of certaincationic surfaceactive sulfonium salts and that this increase in speedis not accompanied by an increase in graininess. Fog in the emulsions sosensitized may be reduced by the use of fog inhibiting agents such astetraazaindenes.

Sulfonium salts which we may use are trialkyl sulfonium salts in whichone alkyl group contains more than 8 carbon atoms, preferably from 9 to16 carbon atoms.

The anion of our compounds may be any acid radical not injurious tophotographic emulsions, for example, ptoluene sulfonate, chloride,bromide, iodide, perchlorate or alkyl sulfate. The introduction ofhalide anions into photographic silver halide emulsions alters thehalide concentration in the emulsion and compensating changes in theemulsion may be desirable if such salts are employed. For this reason,we ordinarily prefer to employ compounds containing anions other thanhalides. Perchlorates and p-toluene sulfonates are advantageouslyemployed.

The sulfonium salts which we propose to use have the general structure:

where R and R represent alkyl groups, e. g., methyl, ethyl, propyl,butyl, etc., or aralkyl groups, e. g., benzyl,

R represents an alkyl group of more than 8 carbon atoms, e. g., nonyl,decyl, dodecyl, tetradecyl, cetyl, etc., and

X represents an anion, e. g., chloride, bromide, iodide, per-chlorate,p-toluene sulfonate, alkyl sulfate, etc.

Specific compounds which we may employ are:

Dimethyl n-nonyl sulfonium p-toluene sulfonate Dimethyl n-decylsulfonium p-toluene sulfonate Dimethyl n-dodecyl sulfonium p-toluenesulfonate Dimethyl n-tetradecyl sulfonium p-toluene sulfonate Diethyln-dodecyl sulfonium p-toluene sulfonate Benzyl ethyl n-dodecyl sulfoniumethosulfate The surface-active sulfonium salts used according to ourinvention may be made as described in U. S. Patents 2,090,890 and2,121,823. This method involves, in general, the treatment of a dialkylsulfide, such as methyl-ndodecyl sulfide, with an alkyl salt such asdimethyl sulfate or methyl bromide. The dialkyl sulfides are made bytreating a higher alkyl mercaptan, e. g., n-dodecyl mercaptan, with analkyl salt such as dimethyl sulfate or methyl bromide. The higher alkylmercaptans may be made by treating an alkyl bromide such as laurylbromide with thiourea (Drake, Organic Syntheses, vol. 21, page 36, 1941)or with sodium hydrosulfide (Organic Syntheses, Collective, vol. 2, page547).

The quantity of surface-active sulfonium salt which is mostadvantageously employed varies with the nature of the surface-activesubstance and-with the nature of the emulsion. Ordinarily, the mostadvantageous concentra: tion has been found to be between about 25 mgs.and 1000 mgs. of the surface-active sulfonium salt per gram mole ofsilver halide in the emulsion, although greater or smallerconcentrations can be employed. We have found that excesses of thesurface-active sulfonium salt are to be avoided since excesses producefog in the emulsions. The optimum range of concentration for anyparticular sulfonium salt described herein is ordinarily fairly narrowand can best be determined by employing a series of concentrations ofthe sulfonium salt separately in several batches of the same emulsionand determining the sensitivity of the several batches before and afterincorporation of the sulfonium salt, in the usual manner which is, ofcourse, well known to those skilled in the art.

The alkylene oxide polymers used to sensitize the emulsions may be ofvarious types. The alkylene oxides from which the polymers are derivedcontain from 2 to 4 carbon atoms, e. g., ethylene oxide, propylene oxideand butylene oxide. The preparation of polymers from these compounds isdescribed in Ellis, The Chemistry of Synthetic Resins (1935), pages 990to 994. These compounds are also referred to as polyalkylene glycols andtheir use as sensitizers for silver halide emulsions is described in U.S. Patents 2,423,549 and 2,441,389. The alkylene oxide derivatives maybe prepared by condensing an organic compound containing an activehydrogen atom with an alkylene oxide polymer, or by condensing theactive hydrogen compound with the alkylene oxide during thepolymerization of the latter material.

Various derivatives of alkylene oxides may also be used! to sensitizethe emulsions, e. g., condensation products of alkylene oxide withorganic compounds containing an active hydrogen atom. Examples of activehydrogen, organic compounds, i. e., compounds in which a hydrogen atommay be replaced by reaction of the compound with metallic sodium,methylmagnesium iodide, etc., in clude alcohols, amines, mercaptans,acids, amides, hydrocarbons such as acetylene, and compounds having theactive hydrogen in a methylene group such as dibenzoyl 3. methane. Morespecifically, we may employ condensation products otalkyleneoxide withglycols such as those having from 8 to 18 carbon atoms as described inU. S. Patent 2,240,472 and British Patent 443,559 as well ascondensation products of alkylene oxides with aliphatic alcohols,condensation products of alkylene oxides with aliphatic acids, e. g.,lauric acid and glycine, condensation productsof a-lkylene oxideswithaliphatic amines or amides, e. g., glycine and lauryl amide, andcondensation products of alkylene oxides with phenols,- e. g., phenol.Thepreparation of these condensation products is described in U; S;Patent 1,970,578: Condensation products of alkylenemxideswith hexitolring'dehydrationproducts as described in U. S. Patent 2,400,532 may alsobe employed.

In eachca sev the polyalkylene oxide or derivative of alkylene oxideshould have a molecular weight of at least 300. Condensation products ofet-hylene'oxide with long chain alcohols, acids, amines or amides shouldhave a molecular, weight of about 700. In general the best results areobtained with the, condensation products of ethylene oxide with longchain compounds having a chain length of 112 or more carbon atoms andwith ethyl-. ene oxide polymers having a molecularv weight of-l500 to4000 or more.

When employing optically sensitized, emulsions the optical sensitizingdyes are advantageously employed in about their optimum concentrationwhich ordinarily lies between about 10 mgs. and 40 mgs. of opticalsensitizing dye per liter of emulsion containing about 0.25 gram moleof'silverhalide although concentrations above or below, the optimumconcentration can be employed.

The alkylene, oxide derivatives used to sensitize the emulsions may beillustrated by the following specific examples, although our. inventionis in no way limited to the use of these specific compounds.

HO CH CH O (CHgCH O ,CH,CH OH- Polyethylene oxide (CH2CH2O)CH2CHOH.

0(GHzCHgO)nOHgOHOH Di- (polyethylene-glycoxy) -decane HQCH CH O (CH CHO) CH2CH OC1qH33 Polyethylene oxide oleyl ether where n=an integergreater than about '10.

The preparation .of silver halide emulsions involves three separateoperations: (1) the emulsification and digestion or ripening of thesilver halide, (2) the freeing of theemplsion from aqueous soluble saltsusually by washing, (3') the second. digestion or after-ripening toobtain increased sensitivity (Mees, The Theory of the PhotographicProcess, 1942, page 3). The sensitizing agents maybe added at any stage,preferably after the final dis st n- The photographicernnlsions which weuse are of the developing-out type and best results have beenobtainedwith gelatino silver bromoiodide emulsions. However, emulsionsof varyinghalide, content may be used.

The emulsions may be chemically sensitizedby any of theacceptedprocedureain addition to or in combinationwith the sensitizing.with alkylene oxidepolymers. The emulsions may .bedigestedwith naturallyactive gelaw tin, or sulfur compounds may be added such,as thosedescribedin Sheppard U, S. Patents 1,574,944 and 1,623,- 49 9, andSheppard and Brigham U. S. Patent 2,410,689.

The emulsions mayalso be treated with salts of the no ble metals such,as ,ruthenium,rhodiumnpalladium, iridium andplatinum, all ofwhich belongtogroup VIII of the periodic table of elements andhave an atomic weightgreaterthan- 100., Representative compoundsare am,-

rnonium; chloropalladate, potassium, chloroplatinate. and.

sodium chloropalladite, which are used for sensitizing in '4 amountsbelow that which produces any substantial fog inhibition, asdescribed'in Smith and Trivelli U. S; Pat ent 2,448,060, and asantifoggants in higher amounts, as described in Trivelli and Smith U. S.Patents 2,566,245 and 2,566,263.

The emulsions may also be chemically sensitized with gold salts asdescribed in Waller and Dodd U. S. Patent 2,399,083, or stabilizedwithgold salts as described in Damschroder U. S. Patent 2,597,856 andYutzy and Leermakers U. S. Patent 2,597,915. Suitablecompounds arepotassium chloroaurite, potassium aurithiocyanate, potassiumchloroaurate, auric trichloride andZ-aurosulfobenzothiazole methochloride.

The emulsions may also be chemically sensitizedwith reducing agents suchas stannous' salts. (Carroll U. S. Patent 2,487,850), polyamines such asdiethylenetriamine (Lowe andJones U. S. Patent 2,518,698), polyarninessuch as spermine-(Lowe-and'Allen U. S. Patent 2,521,925), orbis-(,B-aminoethyl) sulfide and its watersoluble salts (Lowe-andl'onesU. S Patent 2,521,926).

The emulsions may also be stabilized withthemercury compounds of Allen,Byersand-Murray U. S.-.applicati0n.-

Serial No. 319,611, Carrolland Murray U. S. application Serial No.319,612 andjLeubner and Murray U, .S. application Serial No. 319,613,all filed November 8, 1952.

Other stabilizing, agents may be. addedto. 'theemulsions containingthesulfoniumsalts-and alkylene oxide polymers, ,such. as-v cadmium.chloride, cadmium .nitrate,

cobalt nitrate, manganese chloride, manganese sulfate, zinc chloride,zinc nitrate and zinc sulfate.

When using the combination of the. sulfonium salt and the ethylene oxidepolymer for. sensitizing photographic emulsions. thev fog was. foundtobe. increased. on. both.

fresh andvincubated. samples-of the developedemulsion- This fogwas-.reducedto normal levels byuseofan anti.- foggant such as a4-hydroxy-6-alkyl-1,3,3a,7-tetraazain dene, specifically4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, or5-carboxy-4-hydroxyl,3,3a,7-tetraazaindene..

The. following examples illustrate the methodwof staw bilizingemulsionsaccording to our invention:

EXAMPLE 1 A negative-speed gelatino-silver bromoiodide emulsion was.digested with a sulfur compound such'as disclosed in Sheppard U. S.Patent 1,574,944 and' potassium chloro-- aurate. Different portions ofthis emulsion were sensitized with varying amounts of the condensationproduct of 1 mole of'oleyl alcohol with approximately 15 molesofethylene oxide (polyethylene glycol oleyl ether), the amountsusedbeing shown in the following tables. Portions of these'emulsionswereadditionally sensitized with lowing composition:

Grams N-methyl-p-aminophenol sulfates -2 2.5 Hydroquinone 2.5 Sodiumsulfite (desiccated) 30 Sodium metaborate 10 Potassium bromide 0.5

Water to 1 liter.

for speed, gamma and fog before and after incubationof each of thesamples, speed. being read. as. 30/E where E is the exposure in metercandleseconds required .tocpro: duce. a density of 0.2 over fog, .wereas. follows:

Table I.-Plyethylene glycol oleyl ether, 0.7 gram per molesilver halideAgent Fresh Test After Incubation Compound per mole,g

Speed Gamma Fog Speed Gamma Fog Dlmethyl dodecyl sulfonium p-toluenesulto 0 3, .91 .10 3,200 .72 .36 025 3,800 .95 .12 .77 050 4, .95 .14Black .250 .70

Table Il.-Polyelhylene glycol oleyl ether, 0.7 gram per mole silverhalide, +4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, 2 grams per molesilver halide Table IIL-Polyethylene glycol oleyl ether, 0.7 gram permole silver halide, +4ehydroxy-6-methyl-l,3,3a,7- tetmazaindene, 2 gramsper mole silver halide-l-panchromatic sensitizing dye Agent Fresh TestAfter Incubation Compound per mole, g.

Speed Gamma Fog Speed Gamma Fog Dimethyl dodecyl sulfonium p-toluenesulfonate 0 7, 900 97 18 7, 050 97 18 D 025 8, 050 1. 03 18 7, 200 90 17050 9, 250 1. 12 18 7, 050 1. 0 17 250 11, 400 1.10 .21 10,400 .08 .24 10 10,900 1.12 .28 Black EXAMPLE 2 (Carbowax 1500 1s a polyethyleneglycol having an aver- This example shows that various polyethyleneglycols are useful in the emulsions of our invention.

A negative-speed gelatino-silver bromoioclide emulsion was digested witha sulfur compound such as disclosed in Sheppard U. S. Patent 1,574,944and potassium chloroaurate. A portion of this emulsion was sensitizedwith dimethyl dodecyl sulfonium p-toluene sulfonate, 0.3 gram per mol ofsilver, and a separate portion was stabilized with 4-hydroxy 6 methyl1,3,3a,7 tetraazaindene, 1.5 grams per mol of silver. Portions of theseemulsions were mixed and additionally sensitized with variouspolyethylene glycols, and all of the emulsions were coated, exposed anddeveloped as in Example 1. The results of tests for speed, gamma and fog(fresh tests) were as follows:

age molecular weight between 500 and 600. Carbowax 4000 is a hard, waxypolyethylene glycol resembling paraflin in appearance, but iswater-soluble. Both are sold by Carbide and Carbon Chemicals Corp., NewYork city.)

EXAMPLE 3 This example shows the results of using various sulfoniumsalts.

A negative-speed gelatino-silver bromoiodide emulsion was digested witha sulfur compound such as disclosed in Sheppard U. S. Patent 1,574,944and potassium chloroaurate, and was panchromatically sensitized. Thisemulsion was sensitized with the condensation product of 1 mole of oleylalcohol with approximately 25 moles of ethylene oxide (polyethyleneglycol oleyl ether), 0.75 gram per mol of silver, and stabilized with4-hydroxy-6- methyl-1,3,3a,7-tetraazaindene, 4 grams per mol of silver.To portions of this emulsion there were added various amounts of severalsulfonium p-toluene sulfonate salts as shown in the following table.

The emulsions were coated, exposed and developed as in Example 1, andresults of tests for speed, gamma and fog (fresh tests) were as follows:

Agent Compound per Speed Gamma Fog mol, g.

Cheek (Polyethylene glycol and azainden 9, 500 1. 18

Dimethyl nonyl sulionium p-toluene sulfonate 0. 3 700 1. 01 18 Do 0.610.200 1. 00 .18 DO 1.2 10, 900 1.04 .19 Dimethyl decyl Sulfoniump-toluone sulionate 0.3 10, 900 1.03 18 Do... 0.6 11,400 1.06 .19 Do 1.2 11, 900 1.06 .19

Dimethyl dodecyl sullonium p-toluene sulionate 0. 13, 100 1.05 .21 Do0.3 13, 700 1. 25 22 D0 0. 6 14, 700 1. 31 25 Dlmethyl tetradeeylsulionlum p' toluene snlfonate O. 06 11, 900 99 D0 0. 12 12, 200 1.08 22D0 0. 32 13, 400 l. 15 .26

EXAMPLE 4 This example shows the results of using still other sulfoniumsalts.

An emulsion was made and tested as in Example 3; except that 3 grams permol of silver of 4-hydroxy-6- methyl-l,3,3a,7-tetraazaindene was usedand no poly ethylene glycol was added initially. Tests forspeed, gammaand fog (fresh tests) gave the following results:

The increase in speed according to our invention may also be obtained byadding the sulfonium salt to the developer. ratherthan: to* theemu'lsion..- The? present examplesh'ows the improvement-obtained inthis'way.

An emulsion was-made: as in Example 3,, except that no azaindene wasadded to the-emulsion-initially. To a portion of. this-emulsion-beforetesting. there 'wasadded one gram of4-hydroxy-6-methyl-l,3,3a,7-tetraazaindene per mol of silver.

Each of the emuisionswas. exposed and developed for 12 minutes in adeveloperofExample 1, and in this developer to which had been addedvarious quantities of dim'ethyl dodecyl sulfoniu'ntp toluene' sulfonate.Speeds were measured as 100( l-log E), where 1 is the exposure inmetercandle secondsi-requiredto produce-a density of 8 0.3 above 'fog,and the results of tests for speed and fog were tabulated as follows:

Coating Coating polyeth. polyeth. glycol glycol azaindene Speed FogSpeed Fog DeveloperofExamplel u... 339 .as 347 .40 361 .50 379 .51

0 gave the results shown in the following table:

v Coating Coating Develpolyeth'. poiyeth opulent glycol glycol time,azaindene minutes Speed Fog Speed Fog 3 293 .31 298 .31 Developer ofExample 1 5 315 33 319 .35 8 327 .35 337 .36 Developer mg. per liter 3315 .32 319 .33 dimethyl n-decyl sulionlum 6. 332 34' 338 36 p. t; s...8, 343 39 349 .43 Developer mg. per liter 3 312 .33 317 .34 dimethyln-decyl sulionlum 5 330 .34 335 .35 p. t. s 8, 337 .38, 339 .42Developer 50 mg. per liter 3' 324 .34 331 .34 diethyl lauryl sulfonium 5339 .37 345 .40 p. t. s 8 346 .45 352 .48

Improved results may also be obtained by bathing the exposed emulsion ina solution of the sulfonium salt, preferably containing potassiumbromide, prior to developme'iit.

EXAMPLE 6' The increase in speed according to our invention may beobtained by adding the sulfonium salt to the emulsion and thepolyethylene glycol to thedeveloper. The present example shows theimprovement obtained in this way.

An emulsion was made and tested as in Example 3, except that nopolyethylene glycol was added to the emulsion, and the amount of4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene was 1.5 grams per mol ofsilver. To portions of this emulsion: dimethyl dodecyl sulfoniump-toluene s ulfonate was added in the concentrations shown in thefollowing table.

Each of the emulsions was developed after exposure, in the developer ofExample 1 and in this developer to which had been added 2 gramspoi-liter of polyethylene glycol oleyl ether. The results of tests forspeed and fog aeeasso 9 EXAMPLE 7 sulfonate, 0.3 gram per mole ofsilver. To portions of the emulsion containing both the polyethyleneglycol and the sulfonium salt there were added various amounts ofcadmium chloride, as shown in the following table. The various emulsionswere coated, exposed and developed as in Example 1, and records made ofthe speed (SO/E), gamma and fog as follows:

Agent Fresh Test Compound per mole Speed Gamma Fo lPolyethylene glycol(I) 7,200 .74 .20 }6,700 .90 .58 .75

The chemical sensitizing agents and other addenda which we havedescribed may be used in various kinds of photographic emulsions. Inaddition to being useful in non-optically sensitized emulsions they mayalso be used in orthochromatic, panchromatic and X-ray emulsions. Theymay be added to the emulsion before or after any sensitizing dyes whichare used. Various silver salts may be used as the sensitive salt such assilver bromide, silver iodide, silver chloride or mixed silver halidessuch as silver chlorobromide or silver bromoiodide. The agents may beused in emulsions intended for color photography, for example, emulsionscontaining colorforming couplers or emulsions to be developed bysolutions containing couplers.

The dispersing agent for the silver halide may be gelatin or othercolloidal material such as collodion, albumin, cellulose derivatives orsynthetic resins.

It will be understood that we contemplate as included within ourinvention all modifications and equivalents falling within the scope ofthe appended claims.

We claim:

1. A light-sensitive silver halide emulsion sensitized with a mixture ofan alkylene oxide polymer selected from the class consisting of (1)polyalkylene glycols and (2) condensation products of alkylene oxidewith organic compounds containing an active hydrogen atom, said alkyleneoxide containing from 2 to 4 carbon atoms and said alkylene oxidepolymer having a molecular weight of at least 300, and a sulfonium salthaving the general formula:

in which R and R are selected from the class consisting of alkyl andaralkyl groups, R represents an alkyl group of more than 8 carbon atoms,and X represents an anion.

2. The light-sensitive emulsion of claim 1 containing as a foginhibiting agent a 4-hydroxy-6-alkyl-1,3,3a,7-tetraazaindene.

3. The light-sensitive emulsion of claim 1 in which the alkylene oxidepolymer is an ethylene oxide polymer.

4. The light-sensitive emulsion of claim 1 in which the alkylene oxidepolymer is polyethyleneglycol oleyl ether.

5 The light-sensitive emulsion of claim 1 in which the sulfonium salt isn-dodecyldirnethyl sulfonium-p-toluene sulfonate.

6. The light-sensitive emulsion of claim 1 in which the alkylene oxidepolymer is polyethylene glycol oleyl ether and the sulfonium salt isn-dodecyl dimethyl sulfoniump-toluene sulfonate.

7. A light-sensitive silver halide emulsion sensitized with a mixture ofpolyethyleneglycol oleyl ether and ndodecyldimethyl sulfonium-p-toluenesulfonate and containing as a fog inhibiting agent4-hydroxy-6-methyl-1,- 3,3a,7-tetraazaindene.

8. The method of increasing the sensitivity of a silver halide emulsion,which comprises exposing said emulsion and developing it in the presenceof an alkylene oxide polymer selected from the class consisting of (1)polyalkylene glycols and (2) condensation products of alkylene oxidewith organic compounds containing an active hydrogen atom, said alkyleneoxide containing from 2 to 4 carbon atoms and said alkylene oxidepolymer having a molecular weight of at least 300, and a sulfonium salthaving the general formula:

in which R and R are selected from the class consisting of alkyl andaralkyl groups, R represents an alkyl group of more than 8 carbon atoms,and X represents an anion, at least one of said alkylene oxide polymerand said sulfonium salt being incorporated in said emulsion prior toexposure.

9. The method of claim 8 in which the alkylene oxide polymer is anethylene oxide polymer and the sulfonium salt is a di-lower alkylsulfonium salt containing a third alkyl group of more than 8 carbonatoms.

10. The method of claim 8, in which the alkylene oxide polymer is apolyethylene glycol and the sulfonium salt is dimethyl alkyl p-toluenesulfonate in which the alkyl group contains more than 8 carbon atoms.

11. The method of claim 8, in which the alkylene oxide polymer ispolyethylene glycol oleyl ether, and the sulfonium salt is n-dodecyldimethyl p-toluene sulfonate.

12. The method of claim 8, in which the alkylene oxide polymer is anethylene oxide polymer and is in the solution used to develop saidemulsion, and the sulfonium salt is a di-lower alkyl sulfonium saltcontaining a third alkyl group of more than 8 carbon atoms and isincorporated in said emulsion prior to exposure.

13. The method of claim 8, in which the alkylene oxide polymer is anethylene oxide polymer and is incorporated in said emulsion prior toexposure, and the sulfonium salt is a di-lower alkyl sulfonium saltcontaining a third alkyl group of more than 8 carbon atoms and is in thesolution used to develop said emulsion.

14. The method of claim 8, in which the alkylene oxide polymer ispolyethylene glycol oleyl ether and 1s 1ncorporated in said emulsionprior to exposure, and the sulfonium salt is a di-methyl alkyl sulfoniump-toluene sulfonate in which the alkyl group contains more than 8 carbonatoms, and is in the solution used to develop said emulsion.

References Cited in the file of this patent UNITED STATES PATENTS2,275,727 Carroll et al. Mar. 10, 1942 2,288,226 Carroll et al. June 20,1942 2,410,690 Smith et a1. -2 Nov. 5, 1946 2,716,062 Carroll et al.Aug. 23, 1955 UNITED STATES PATENT DJFFICE CERTIFICATE OF CORRECTIONPatent No. 2,848,330 August 19, 1.958

Jonas John Chechak 'et a1.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column '7, line 59, aift'er "Where", for "1" read E Signed and sealedthis 18th day of November 1958a (SEAL) Attest:

KARL H. AXLINE Attesting Oflicer ROBERT c. WATSON Commissioner ofPatents

1. A LIGHT-SENSITIVE SILVER HALIDE EMULSION SENSITIZED WITH A MIXTURE OFAN ALKYLENE OXIDE POLYMER SELECTED FROM THE CLASS CONSISTING OF (1)POLYALKYLENE GLYCOLS AND (2) CONDENSATION PRODUCTS OF ALKYLENE OXIDEWITH ORGANIC COMPOUNDS CONTAINING AN ACTIVE HYDROGEN ATOM, SAID ALKYLENEOXIDE CONTAINING FROM 2 TO 4 CARBON ATOMS AND SAID ALKYLENE OXIDEPOLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST 300, AND A SULFONIUM SALTHAVING THE GENERAL FORMULA: